Process of producing alumina.



ENTT- DAVID H. CHILDS, OF ALFRED, NEW YORK.

PROCESS OF PROD compounds in which the aluminum silicate is'present inlarge quantities. For this purpose clay, bauxite .and other compounds cgtaining aluminum silicate may be used,

but'for commercial purposes kaolin is prematerial as any ferred becauseof its abundance and cheapness and also for the reason that it is a clayof a high degree of purity whichcontains a lafge percentage of aluminumsilicate and is practically free from iron and other for- In thetreatment of these materials to produce alumina, it is important thatall the necessaryreactions should take place without requiring fusion ofthe fusion process is slow in operation, requires a thorough calcinationof the material before being treated and entails the employment ofelectric furnaces and other expensive apparatus which greatly increasethe expense of the process and de st-roy its desirability from acommercial standpoint. I I

The objet of this invention ic to provide a process of producing aluminafrom materials containin aluminum silicate' which is simple andinexpensive, requires no fusion of the material and can be successfullyoperated in a commercial manner.

The process consists in mixing the kaolin or other substance to betreated with asuitable amount of aluminum fiuorid which is determined bythe amount of aluminum silicate present in the material used, thosesubstances 'containing a large amount of aluminum silicate, such askaolin, requiring a greater proportional amount of aluminum fiuorid thanthose containing a small ampunt of aluminum silicate, such as! bauxite.Approximately four ounds of aluminum fiuorid are required fiir eachpound of silica, whether free or combined, contained eign substances.

Specification of Letters Patent.

Serial No. 577,280. Renewed June 701,654.

'ing the material.

, calcined UGING ALUMINA.

Patented Aug. 20, 1912.

4. 1 912. Serial No.

used. 'This mixture-is then which is sufiicient in the material heatedto a temperature to cause the fluorin to combine witht the. silica toproduce a volatile; compound of silicon and fluorin which passes off asa gas, leaving aluminum oxid as a solid. The temperature at which thisreaction takes place is considerablyless than that required forproducing a fusion of the material, and this makes it possible to employan oil or gas furnace of common construction for heat- When no Water ispresent in the mixture, water or water vapor is added thereto during theheating operation to facilitate the reaction of the fluorin with thesilica.

In carrying out the process with kaolin, I take a suitable quantity ofaluminum fluorid which has been ground to a fine powder and thoroughlymix itwith about onehalf its weight of kaolin.- Themixture is thenheated, in a suitable oil or gas furnace,

preferably in contact with the flame, to a temperature which must beless than the melting point of alumina and should not exceed 2500 F. Forordinary commercial urposes, a temperature of from 1600 Flto 1800 F. hasbeen found sufiicient to produce the necessary reaction. Atthistemperature the fluorin will combine with the-silica in the kaolin andthe silicon fluorid so formed will pass off as a gas, leaving thealuminum oxid as a solid remaining in the furnace. The temperaturenecessary to produce the reaction varies considerably with the materialtreated and may be greater or less than that above given but is neverhigh enough to produce a fusion of the mixture H The mixture containssome water before but it is advisable,

kaolin is being treated, to add a further quantity of water or watervapor during the heating process to facilitate the react-ion. This maybe done by means of a water or steam jet which is arranged to dischargedirectly into the furnace. The aluminum oxid remaining in the furnace ispracheating,

especially when tically free from all foreign matter and requires nofurther treatment to prepare it for use commercially. I clainr as myinvention};

1. The process. of producing aluminum, oxid from asubstance containingaluminum silicate which consists in mixing such substance with aluminumfluorid and heating the mixture to a sufficiently high temperaturetocause the fluorin to react upon the silica Without causing fusionthereof, and produce a volatilecompound of silicon and fluori'n leavingaluminum oxid as a solid, substantially asset forth.

2.. The process of producing aluminum oXid from a substance containingaluminum silicate Which consists in mixing such substance With aluminumfiuorid-and heating the-mixture in the presence of Water to asufficientlyhigh temperature to cause the fluorin to react upon thesilica Without causing fusion thereof, and produce a volatile compoundof silicon and fiuorin leaving aluminum oxid as a solid, substantiallyas set forth.

3. The process of producing" aluminum oxid from kaolin which consists inmixing the kaolin with aluminum fluorid and heating the mixture to asufficiently high temperature to cause the fluorin to react upon thesilica in the kaolin; without causing leaving aluminum fusion thereof,and produce a volatile compound of silicon and fluorin, leaving aluminumoXid as a solid, substantially as set forth.

4. The process of producing aluminum oxid from kaolin which consists inmixing the kaolin with aluminum fluorid in substantially the proportionof one part in Weight of the'kaolin to two parts in Weight of thefiuorid and hea'tingthe mixture to a temperature of approximately 1600F.'to 1800 F. which causes the fluorin to react upon the silica in thekaolin and produces a volatile compound of silicon and fluorin,

oxid, as asolid, substantially as set forth.

Witness my hand in the presence of two subscribing Witnesses.

- DAVID H; oHILDs.

VVitn'esses:

HORAN MACK, MAUD J oRDaN.

copies of this'patent may be obtained Ior'five cents each, by addressingthe Commissioner of Patent Washington, D. G.

